1975 115hp Lower unit

[dreadinger]

I looking to purchase a 1975 115hp motor this weekend. I am unfamiliar with the hydromechanical shift on these motors, is there any pointers on what to look for? Also, are the throttle and shift cables different from a 1975 and 1992?

 

[crb478]

Re: 1975 115hp Lower unit

The throttle and shift cables are the same. The control boxes were different, but the 1992 will fit and work fine. Are you just buying the lower unit? It will not fit the 1992.
If you are buying the whole motor do a compression check first. You are shooting for over 100psi and even,or within 10 percent, on all four cylinders. If its a little lower, but they are still even it may still be a good candidate since you may be able to bring the compression up. Also pay close attention to the overall appearance and condition. If it looks shot it probably is. Then check for spark see if it will jump a 1/2 or 5/8 inch gap with a strong spark.

You can easily spend more fixing this motor up than it is worth so if it is not priced right and in fairly good shape you might want to pass on it.

 

[dreadinger]

Re: 1975 115hp Lower unit

It is a complete motor with controls that is said to be excellent running condition for 450.00.

 

[ezeke]

Re: 1975 115hp Lower unit

The standard 1975 115 lower units from 1973-1977 85HP and 115HP will bolt on as well as the 1973-1976 135HP. No other units will work. These were very good gearcases that lasted a long time and were easy to service.

You can identify them by the fact that the skegs were 90 degrees from the unit, that the shift rod seal housing is different from other models and that the water pumps have two water tubes rather than one.

Use a high viscosity marine gearcase oil.

The 1973-1977 115 motor's parts were discontinued after 1977 and there is little about them that is compatible with the 115HP motors from 1978 on.